In a silicon semiconductor integrated circuit (LSI), conventionally aluminum (Al) or an Al alloy has been widely used as an electroconductive material. As the tendency of a method for manufacturing finer LSI progresses, copper (Cu) has been used as an electroconductive material so as to decrease the resistance of a wire in wiring and enhance the reliability. This Cu easily diffuses into a silicon oxide film, so that an electroconductive barrier metal film for preventing the diffusion of Cu is used in the side face and the bottom face of Cu wiring, and an insulative barrier film is used in the top face of the Cu wiring.
By the way, as the tendency of refining LSI progresses recently, a wiring dimension has been further refined. Then, a problem has arisen that the capacitance between wirings increases, and an insulating film with a low dielectric constant is progressively introduced for an interlayer insulating film. This is because it is effective not only to refine the wiring but also lower the dielectric constant of the interlayer insulating film, and both methods are required in combination, in order to drive a semiconductor element using a multilayer wiring at a high speed and a low electric power.
In order to decrease the effective capacitance between the wirings in this way, it has been required to lower the dielectric constant of the interlayer insulating film (in this case, silicon oxide film (k=4.2)). Examples of this insulating film with a low dielectric constant include a HSQ (Hydrogen Silsesquioxane) film, CDO (Carbon doped oxide), and an organic film. These insulating films with a low dielectric constant are formed with a spin coating method, a vapor phase method or the like.
Japanese Patent Laid-Open No. 2003-309173 discloses a technology of forming a modified layer by subjecting an organosiloxane film to NF3 plasma treatment and enhancing the adhesiveness.
Japanese Patent Laid-Open No. 2006-24641 discloses a technology of forming a modified layer by subjecting an organosiloxane film to a reducing treatment and protecting the organosiloxane film.
National Publication of International Patent Application No. 2002-526916 discloses a technology of forming a porous insulating film by using a cyclic organosiloxane as a raw material.
Japanese Patent Application No. 2003-400683 discloses a technology of forming a porous insulating film by using a three-membered cyclic organosiloxane as a raw material.